Apparatus and method for minimizing waste and improving quality and production in web processing operations by automatic cuff defect correction

ABSTRACT

Apparatus and methods are provided to minimize waste and improve quality and production in web processing operations. The apparatus and methods provide defect detection both before and after application of component patches to a traveling web to create a product. Web defect detection may be provided by way of at least one visual inspection station located upstream from the patch applicator. Patch defect detection may be accomplished by way of a visual inspection station located proximate the patch applicator. If defects are detected in either the traveling web or the component patch prior to patch application, patch application may be prevented until both a satisfactory web and patch are provided. If defects are detected after patch application, the resulting product may be culled. Furthermore, the apparatus may be provided with diagnostic software to warn against extant or imminent machine complications.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/400,969, filed 5 Aug. 2010.

BACKGROUND OF THE INVENTION

The invention disclosed herein relates to apparatus and methods forwaste reduction and improvements to the quality and production in webprocessing operations, such as diaper manufacturing. While thedescription provided relates to diaper manufacturing, the apparatus andmethod are easily adaptable to other applications.

Generally, diapers comprise an absorbent insert or patch and a chassis,which, when the diaper is worn, supports the insert proximate a wearer'sbody. Additionally, diapers may include other various patches, such astape tab patches, reusable fasteners and the like. The raw materialsused in forming a representative insert are typically cellulose pulp,tissue paper, poly, nonwoven web, acquisition, and elastic, althoughapplication specific materials are sometimes utilized. Usually, most ofthe insert raw materials are provided in roll form, and unwound andapplied in assembly line fashion.

In the creation of a diaper, multiple roll-fed web processes aretypically utilized. To create an absorbent insert, the cellulose pulp isunwound from the provided raw material roll and pulverized by a pulpmill. Discrete pulp cores are formed by a core forming assembly andplaced on a continuous tissue web. Optionally, super-absorbent powdermay be added to the pulp core. The tissue web is wrapped around the pulpcore. The wrapped core is debulked by proceeding through a calendarunit, which at least partially compresses the core, thereby increasingits density and structural integrity. After debulking, thetissue-wrapped core is passed through a segregation or knife unit, whereindividual wrapped cores are cut. The cut cores are conveyed, at theproper pitch, or spacing, to a boundary compression unit.

While the insert cores are being formed, other insert components arebeing prepared to be presented to the boundary compression unit. Forinstance, the poly sheet is prepared to receive a cut core. Like thecellulose pulp, poly sheet material is usually provided in roll form.The poly sheet is fed through a splicer and accumulator, coated with anadhesive in a predetermined pattern, and then presented to the boundarycompression unit. In addition to the poly sheet, which may form thebottom of the insert, a two-ply top sheet may also be formed in parallelto the core formation. Representative plies are an acquisition webmaterial and a nonwoven web material, both of which are fed frommaterial rolls, through a splicer and accumulator. The plies are coatedwith adhesive, adhered together, cut to size, and presented to theboundary compression unit. Therefore, at the boundary compression unit,three components are provided for assembly: the poly bottom sheet, thecore, and the two-ply top sheet.

A representative boundary compression unit includes a die roller and aplaten roller. When all three insert components are provided to theboundary compression unit, the nip of the rollers properly compressesthe boundary of the insert. Thus, provided at the output of the boundarycompression unit is a string of interconnected diaper inserts. Thediaper inserts are then separated by an insert knife assembly andproperly oriented. At this point, the completed insert is ready forplacement on a diaper chassis.

A representative diaper chassis comprises nonwoven web material andsupport structure. The diaper support structure is generally elastic andmay include leg elastic, waistband elastic and belly band elastic. Thesupport structure is usually sandwiched between layers of the nonwovenweb material, which is fed from material rolls, through splicers andaccumulators. The chassis may also be provided with several patches,besides the absorbent insert. Representative patches include adhesivetape tabs and resealable closures.

The process utilizes two main carrier webs; a nonwoven web which formsan inner liner web, and an outer web that forms an outwardly facinglayer in the finished diaper. In a representative chassis process, thenonwoven web is slit at a slitter station by rotary knives along threelines, thereby forming four webs. One of the lines is on approximatelythe centerline of the web and the other two lines are parallel to andspaced a short distance from the centerline. The effect of such slicingis twofold; first, to separate the nonwoven web into two inner diaperliners. One liner will become the inside of the front of the diaper, andthe second liner will become the inside of the back of that garment.Second, two separate, relatively narrow strips are formed that may besubsequently used to cover and entrap portions of the leg-hole elastics.The strips can be separated physically by an angularly disposed spreaderroll and aligned laterally with their downstream target positions on theinner edges of the formed liners.

After the nonwoven web is sliced, an adhesive is applied to the linersin a predetermined pattern in preparation to receive leg-hole elastic.The leg-hole elastic is applied to the liners and then covered with thenarrow strips previously separated from the nonwoven web. Adhesive isapplied to the outer web, which is then combined with the assembledinner webs having elastic thereon, thereby forming the diaper chassis.Next, after the elastic members have been sandwiched between the innerand outer webs, an adhesive is applied to the chassis. The chassis isnow ready to receive an insert.

In diapers it is preferable to contain elastics around the leg region ina cuff to contain exudates for securely within the diaper. Typically,strands of elastic are held by a non-woven layer that is folded overitself and contains the elastics within the overlap of the non-wovenmaterial. The non-woven is typically folded by use of a plow systemwhich captures the elastics within a pocket, which is then sealed toensure that the elastics remain in the cuff.

Most products require some longitudinal folding. It can be combined withelastic strands to make a cuff. It can be used to overwrap a stiff edgeto soften the feel of the product. It can also be used to convert thefinal product into a smaller form to improve the packaging.

To assemble the final diaper product, the insert must be combined withthe chassis. The placement of the insert onto the chassis occurs on aplacement drum or at a patch applicator. The inserts are provided to thechassis on the placement drum at a desired pitch or spacing. Thegenerally flat chassis/insert combination is then folded so that theinner webs face each other, and the combination is trimmed. A sealerbonds the webs at appropriate locations prior to individual diapersbeing cut from the folded and sealed webs.

Roll-fed web processes typically use splicers and accumulators to assistin providing continuous webs during web processing operations. A firstweb is fed from a supply wheel (the expiring roll) into themanufacturing process. As the material from the expiring roll isdepleted, it is necessary to splice the leading edge of a second webfrom a standby roll to the first web on the expiring roll in a mannerthat will not cause interruption of the web supply to a web consuming orutilizing device.

In a splicing system, a web accumulation dancer system may be employed,in which an accumulator collects a substantial length of the first web.By using an accumulator, the material being fed into the process cancontinue, yet the trailing end of the material can be stopped or slowedfor a short time interval so that it can be spliced to leading edge ofthe new supply roll. The leading portion of the expiring roll remainssupplied continuously to the web-utilizing device. The accumulatorcontinues to feed the web utilization process while the expiring roll isstopped and the new web on a standby roll can be spliced to the end ofthe expiring roll.

In this manner, the device has a constant web supply being paid out fromthe accumulator, while the stopped web material in the accumulator canbe spliced to the standby roll. Examples of web accumulators includethat disclosed in U.S. patent application Ser. No. 11/110,616, which iscommonly owned by the assignee of the present application, andincorporated herein by reference.

As in many manufacturing operations, waste minimization is a goal in webprocessing applications, as products having spliced raw materials cannotbe sold to consumers. Indeed, due to the rate at which web processingmachines run, even minimal waste can cause inefficiencies of scale. Inpresent systems, waste materials are recycled. However, the act ofharvesting recyclable materials from defective product is intensive.That is, recyclable materials are harvested only after an identificationof a reject product at or near the end of a process. The result is thatrecyclable materials are commingled, and harvesting requires the extrastep of separating waste components. Therefore, the art of webprocessing would benefit from systems and methods that identifypotentially defective product prior to product assembly, therebyeliminating effort during recyclable material harvesting.

Furthermore, to improve quality and production levels by eliminatingsome potentially defective product, the art of web processing wouldbenefit from systems and methods that ensure higher product yield andless machine downtime.

SUMMARY OF THE INVENTION

Provided are method and apparatus for minimizing waste and improvingquality and production in web processing operations.

Importantly, the methods taught in the present application areapplicable not only to diapers and the like, but in any web basedoperation. The waste minimization techniques taught herein can bedirected any discrete component of a manufactured article, i.e., themethods taught herein are not product specific. For instance, thepresent methods can be applied as easily with respect to diapercomponents as they can for feminine hygiene products, as they can forface masks in which components such as rubber bands and nose pieces areused.

For instance, by practicing the methods of the present invention, wasteof staples and elastic bands can be avoided during manufacture of facemasks, for instance those disclosed in U.S. Pat. No. 7,131,442. One ofthe objectives is simply to recognize product during manufacture thatultimately would fail quality control inspection, and avoid placingmaterial on to that product during the manufacturing processes.

As another example, the amount of adhesive applied to certain productscan be reduced by not applying adhesive to products that have alreadybeen determined to be defected or assigned to rejection. For instance,in U.S. Pat. No. 6,521,320, adhesive application is shown for example inFIG. 11. By assigning or flagging product that has already beendetermined to end up in a scrap or recycling pile, the adhesive flow canbe stopped or minimized

In yet another exemplary application of the methods of the presentinvention, discrete components or raw material carried on products thathave already been determined to be defected or assigned to rejection canalso be removed and recycled prior to commingling with other discretecomponents or raw material. For instance, if an absorbent pad, such asshown at reference numeral 40 of U.S. Pat. No. 6,521,320 is destined forapplication to a product that has already been determined to be defectedor assigned to rejection, the absorbent pad can be withdrawn from theproduct, or never introduced in the first instance. For example, duringstartup or shutdown of high speed diaper manufacturing operations, acertain number of products is routinely discarded into recycling. Byidentification of the start up or shut down routine, avoidance ofintroduction of absorbent pads can be achieved. Alternatively, duringstand-by, the absorbent pads often degrade by accumulation of dust. Byidentifying which products would bear the dust, the absorbent pads canbe withdrawn from further manufacture, and no additional componentswould be applied to such a product.

In one embodiment, a method for assembling a plurality of continuouswebs is provided, including defining first web inspection parameters andinspecting at least one of the plurality of continuous webs to determinewhether the at least one web conforms to the first web inspectionparameters. Further, the method involves providing a chassis web whichis adapted to receive a patch and providing a patch web from which thepatch is cut. Finally, the cut patch is applied to the chassis web ifthe inspected web conforms to the first web inspection parameters. Inanother embodiment, the method also includes steps of defining firstpatch inspection parameters and inspecting a cut patch to determinewhether the patch conforms to the first patch inspection parameters.While the patch inspection may provide interesting diagnosticinformation related to a web processing machine, the application of thepatch may be limited to those patches that conform to the first patchinspection parameters.

Another embodiment of the method of the present invention involvesdefining first web inspection parameters and a product pitch. Generallyin any web process, a web is provided, which is traveling at a webvelocity. This embodiment involves inspecting the web to determinewhether the web conforms to the first web inspection parameters andproducing an inspection value as a result of the inspecting step. Thisvalue is then recorded once per sample time interval. The sample timeinterval may be calculated by dividing the defined product pitch by theweb velocity. While the inspection value may be as simple as a bivalentvalue, a more informational multivalent value may be used.

In addition to the web process provided, an apparatus for carrying outthe process is provided. An embodiment of the apparatus includes acontinuous web supply providing continuous web material from an upstreamposition to a downstream position and a means for providing a patchspaced from a first side of the continuous web material. A patchapplicator is provided to alter the space between the patch providingmeans and the continuous web material and a web inspection device ispositioned upstream from the patch applicator. Additionally, aprogrammable controller receives an input from the web inspection deviceand provides an output to the patch applicator. The web processingapparatus may also include a patch inspection device that provides anoutput to the programmable controller. A patch reject conveyor may bepositioned to receive defective patches from the patch providing means.In another embodiment of a web processing apparatus, a productinspection device may be located downstream from the patch applicator toprovide an output to the programmable controller. Also, a product rejectconveyor could be adapted to divert defective product as indicated bythe product inspection device.

One aspect of the present invention involves automatically correctingany cuff folding defects. Before entering the cuff folding system, thecuff material is first slit into two even width strips and then passesthrough a web guide. The cuff fold is created by passing the materialover the elastic guide roller. Part of the cuff web extends over theedge of the elastic guide roller; it is this portion of cuff that isfolded back on top of itself. As the cuff web passes over the elasticroller guide, two adhesive coated strands of elastic are laid down ontop of the cuff web just before folding. The fold is completed as thecuff passes over the folding board with the elastic strands inside thefold. The cuff next passes over the chill roll to set the adhesive.During the folding of the cuff non-woven, the non-woven can becomeoperatively disengaged with the plow, causing the overlap not to beformed, resulting in a product defect by which the cuff elastic is notcaptured within a pocket in the non-woven.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a representative web processing system;

FIG. 2A-2C are schematic representations of a web processing systemincorporating principles of the present invention;

FIG. 3 is an elevation view of a patch inspection;

FIG. 4 is a perspective view of a patch indexer, a patch applicator anda patch reject conveyor;

FIG. 5 is a schematic of a second embodiment of a representative webprocessing system;

FIG. 6A-6C are additional schematic representations of a web processingsystem incorporating principles of the present invention;

FIG. 7 is a side view of an automatic cuff defect correction system ofthe present invention;

FIG. 8 is a top view of a retractable plow system used to assist, and acomponent of, an automatic cuff defect correction system of the presentinvention;

FIG. 9 is a side view, of a portion of automatic cuff defect correctionsystem of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention which may be embodied inother specific structures. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

It is noted that the present waste minimization techniques and apparatusare described herein with respect to products such as diapers, but aspreviously mentioned, can be applied to a wide variety of processes inwhich discrete components are applied sequentially.

Referring to FIG. 1, a web processing operation starts withincorporating raw materials such as paper pulp and super absorbentpolymer (SAP) in a pulp mill. The mixture is sent to a core formingdrum, where cores are formed for retaining liquids. A core can be placedon a tissue and processed as shown. Eventually, an additional tissuelayer is formed, sandwiching the core.

The process continues through debulking, core cutting and spacing,optionally, compression, and application of tape and elastics. Theprocess then proceeds with application of outer and inner non-wovenlayers, and waist elastic. The web can undergo folding, extraction andtrimming of excess material, and application of material to tighten thediaper about the waist. Eventually, the product is folded and packaged.

As seen on FIG. 1, the

symbol is shown at locations of introductions of discrete componentsinto the process. At these locations, inspection can take place todetermine the presence or absence of acceptable product introduction. Inaddition to visual inspection, operational characteristics such asstartup/ramp-up/shutdown operations can trigger waste minimizationtechniques as will be described later.

At each of these operations shown in FIG. 1, diagnostics can beperformed to indicate whether the product meets acceptable criteria. Ifso, discrete elements, such as the core, tissue layers, elastic, etc.,continue to be applied in a sequence such as shown in FIG. 1. If not, noadditional discrete elements need be applied.

Referring now to FIGS. 2a-c, a web processing operation incorporatingthe present invention is shown.

Referring now to FIG. 2, an additional schematic of processes of thepresent invention is shown. As indicated, pulp rolls 200 feed raw pulp201 into a pulp mill 204, where the pulp is pulverized. Super absorbentpolymer is added from station 206. The SAP laced pulp is fed onto coreforming roller 208. Cores 210 from core forming roller 208 are appliedto the tissue back sheet 214 which has been introduced through tissueback sheet feeder 212. Following debulking station 216 and core cuttingand spacing station 218, an infeed of poly layer 220, elastic layer 222is applied to the carrier web, in addition to non woven layer 224 andtwo ply top sheet woven 226. This web then is cut at cutting station 228into discrete inserts 230, which are then typically placed on a articletransfer and placement apparatus with active puck 230, such as thatdisclosed in U.S. Pat. No. 7,770,712, owned by the same assignee as thepresent case, and which is incorporated herein by reference.

The process utilizes two main carrier webs; a nonwoven web 11 whichforms an inner liner web, and a web 12 that forms an outwardly facinglayer in the finished diaper 50. In this embodiment, the nonwoven web 11is slit, at slitter station 15, by rotary knives 14 along three lines.One of these lines is preferably on approximately the centerline of web11 and the other two lines are parallel to and spaced a short distancefrom the centerline. The effect is twofold; first, to separate web 11into two inner liners 20. One liner will become the inside of the frontof the diaper 50 and the second liner will become the inside of the backof that garment. Second, two separate, relatively narrow strips 22 and24 are formed which are subsequently used to cover and entrap portionsof leg-hole elastics 26. Strips 22 and 24 are separated physically by anangularly disposed spreader roll 23 and aligned laterally with theirdownstream target positions on the inner edges of the liner webs 20.

Adhesive patterns are applied to the liner webs 20 in target areas forthe leg-hole elastics 26. A spray gun assembly 29 of a type known in theart is preferably used to apply the adhesive patterns. Two sets ofleg-hole, elastic strands 26 are introduced through laydown guides 30,which reciprocate from side to side past each other. The strands 26 areglued to the web sections 20, their laydown patterns following aserpentine path. Given the absence of adhesive in the area separatingthe inner liners 20, for some portion of each successive diaper product,the strands 26 each track parallel to the inner slit edges of the websections 20. Laydown guides 30 then apply the strands 26, which formleg-hole elastics as the web sections 20 are carried along the face of adrum or roll 32. Those parts of the elastic patterns which are near theinner slit edges of webs 20 are then covered by the introduction of anadhesive lamination thereover of the strips 22 and 24 of nonwoven webalso against the drum 32.

The side-to-side excursions of the leg-hole elastic lay-down guides 30result in arcuate segments of elastic strands extending on each side ofthe web centerline. After the nonwoven strips 22 and 24 have beenapplied to cover and entrap those parts of the elastics 26 that runnearest to and parallel to the inner edges of the webs 20, a second pairof slitter knives 34 is used to trim away a portion of the narrownonwoven strips 22, 24, along with that part of the inner liner webs 20to which they are laminated. This also removes those portions of theelastic strands 26 which are contained within the laminations. Theresultant trimmed scrap strips 36 are removed from the process fordisposal elsewhere.

The effect of the last-described step is to remove the cut away portionsof the elastic, eliminating its corresponding unwanted gathering effectfrom the crotch region of the garments 50. The remaining portions of thecurved elastic strands create a gathering effect around the leg openingsof the finished garments 50.

Subsequent to the combining and trimming of the inner webs 20 and thecover strips 22, 24, the combining drum 32 carries the webs to a nipwith a second combining drum 38, where the web sections 20, with theirrespective curved elastic patterns exposed, are transferred to andlaminated adhesively against the inside face of outer liner web 12. Thisprocess entraps the curved elastic patterns 26 between the inner liners20 and outer web 12 thereby forming a composite web 39.

The composite web 39 is then provided with a pattern of adhesive inpreparation to receive an absorbent insert or patch 46. The patch 46 iscut from a provided patch web 40 by a cooperation of a cutter 41 and ananvil surface on a vacuum roll 42 and rotated into position for transferto the composite web 39 by a patch applicator 105. If the patch 46 is tobe applied to the web 39—a determination explained more fully below—thepatch applicator 105 forces the web 39 against the patch 46, therebyadhering the patch 46 to the web 39.

Leg-hole materials 48, if not previously removed, are cut at a cuttingstation 47, thereby removing the material 48 contained within anapproximate perimeter defined by the curved pattern of the elastics 26.The running composite chassis web 39 is folded, before or after cuttingout of the leg holes, longitudinally along its centerline, therebygenerally aligning its front waist edge with its back waist edge. Theregions 53 which are to become the side seams 54 of the garments 50 arethen welded by a sealing device 49 either ultrasonically or by heat.Note that the leg holes are preferably cut out before this point,leaving only a narrow zone for welding. The weld pattern is preferablywide enough to extend into both the left side seam of one garment andthe right side seam of the adjacent garment. The garments 50 are thenseparated by passing through a cut-off knife assembly 55, which seversthe web along the transverse axis of the side seam weld 53.

In addition to the exemplary components generally found in a webprocessing apparatus, the present device and methods further include anadvanced defect detection system. An embodiment of the defect detectionsystem preferably comprises at least one visual inspection station 101,but preferably a plurality of visual inspection stations 101. Eachvisual inspection station 101 may include a vision sensor, such as anIn-Sight Vision Sensor available from Cognex Corporation of Natick,Mass. Since each component part of a product resulting from a webprocess has a point of incorporation into the product, visual inspectionof each component part preferably occurs prior to the point ofincorporation. The results of the visual inspections that occur arerelayed from each visual inspection station 101 to a programmable logiccontroller (PLC) 103. Each visual inspection station 101 may providediagnostic capability by monitoring lighting, focus and positioning.

Machine vision systems typically require digital input/output devicesand computer networks to control other manufacturing equipment, in thiscase the splicing unit.

A typical machine vision system will consist of several among thefollowing components:

-   -   One or more digital or analog camera (black-and-white or color)        with suitable optics for acquiring images    -   Lighting    -   Camera interface for digitizing images (widely known as a “frame        grabber”)    -   A processor (often a PC or embedded processor, such as a DSP)    -   Computer software to process images and detect relevant        features.    -   A synchronizing sensor for part detection (often an optical or        magnetic sensor) to trigger image acquisition and processing.    -   Input/Output hardware (e.g. digital I/O) or communication links        (e.g. network connection or RS-232) to report results    -   Some form of actuators used to sort or reject defective parts.

The sync sensor determines when a part (often moving on a conveyor) isin position to be inspected. The sensor triggers the camera to take apicture of the part as it passes by the camera and often synchronizes alighting pulse. The lighting used to illuminate the part is designed tohighlight features of interest and obscure or minimize the appearance offeatures that are not of interest (such as shadows or reflections).

The camera's image can be captured by the framegrabber. A framegrabberis a digitizing device (within a smart camera or as a separate computercard) that converts the output of the camera to digital format(typically a two dimensional array of numbers, corresponding to theluminous intensity level of the corresponding point in the field ofview, called pixel) and places the image in computer memory so that itmay be processed by the machine vision software.

The software will typically take several steps to process an image. Inthis case, the image processing will result in either detection of theindicator material, or non-detection of the indicator material.

Commercial and open source machine vision software packages typicallyinclude a number of different image processing techniques such as thefollowing:

-   -   Pixel counting: counts the number of light or dark pixels    -   Thresholding: converts an image with gray tones to simply black        and white    -   Segmentation: used to locate and/or count parts    -   Blob discovery & manipulation: inspecting an image for discrete        blobs of connected pixels (e.g. a black hole in a grey object)        as image landmarks. These blobs frequently represent optical        targets for machining, robotic capture, or manufacturing        failure.    -   Recognition-by-components: extracting geons from visual input    -   Robust pattern recognition: location of an object that may be        rotated, partially hidden by another object, or varying in size    -   Barcode reading: decoding of 1D and 2D codes designed to be read        or scanned by machines    -   Optical character recognition: automated reading of text such as        serial numbers    -   Gauging: measurement of object dimensions in inches or        millimeters    -   Edge detection: finding object edges    -   Template matching: finding, matching, and/or counting specific        patterns.

In most cases, a machine vision system will use a sequential combinationof these processing techniques to perform a complete inspection. Asystem that reads a barcode may also check a surface for scratches ortampering and measure the length and width of a machined component.

Additionally, machine downtime can be minimized by the provision ofsystems and methods for warning a machine operator of expected machinetroubles so that scheduled maintenance can occur.

The PLC 103 includes software adapted to run several routines that maybe initiated by some triggering event, such as an automatic detection ofa defined condition or manual input by a machine operator. Some routinesare run during machine setup while other routines are run during machineoperation, while still other routines are run during machine diagnosticsat some point during machine downtime.

The PLC 103 generally receives inputs 120 from the visual inspectionstations 101, from the various machine components, or from manual inputby a machine operator on an operator interface, or human machineinterface (HMI) 115. Some of the inputs can also be from stations nearthe pulp rolls, pulp mills, forming rollers, or elsewhere in the systemwhere inspection is present.

The HMI 115 provides an interface for user interaction with the webprocessing machinery and may comprise a pressure sensitive touch screen,a keyboard, a computer mouse, or even a wireless device providing suchan interface. The PLC 103 preferably provides controlling outputs 121 tothe patch applicator 105, the cutter 41 and vacuum roll 42, a patchreject conveyor 107 and a product reject conveyor 109.

The input to the PLC 103 from each inspection station 101 preferablycomprises a defect indicator 111 that represents a detected web defectat a position in the process a number of patch placements from the patchapplicator 105. That is, at any given time during machine operation,between any inspection station 101 and any patch applicator 105 in a webprocess, there exists material sufficient to produce a determinablenumber of products having a patch applied thereto. Therefore, a defectmay be detected and flagged as corresponding to a specific productlocation throughout the process.

In determining whether a patch should be applied to a product by a patchapplicator 105, the PLC 103 stores a product status indicator for eachproduct in the process, preferably for each product between the productreject conveyor 109 and most remote visual inspection station 101. Thestatus indicator accumulates defect indicators 111 from the inspectionstations 101 to track the progress of a product through the process.

A preferred product status indicator is a byte of digital data, witheach bit reflecting the defect indicator 111 for the tagged product froman inspection station 101. For example, the least significant bit in thestatus indicator may represent the defect indicator for the most remotevisual inspection station 101. As the bit significance increases, sodoes the proximity of the respective inspection station 101 to theproduct reject conveyor 109. A byte of data would provide for thepossibility of eight inspection stations, and specific tracking ofdefects at those inspection stations. To store the product statusindicator, the PLC 103 preferably includes some volatile and somenonvolatile computer memory. The volatile memory may provide quickeraccess times during machine operation, while the nonvolatile memorycould be used to store product status indicators when the machine ispaused. The minimum amount of memory required by the PLC 103 is at leastpartly determined by the number of visual inspection stations 101 andthe number of potential products in queue between the first visualinspection station 101 and the product reject conveyor 109. For example,if a web process utilizes eight visual inspection stations 101 and twohundred products could be in queue in any given time, a volatile memoryof at least two hundred bytes would be required.

The visual inspection station outputs may be sampled synchronously, orthe outputs may be asynchronously analyzed by the PLC 103. Ifsynchronous, the outputs may be sampled at a rate equal to the speed ofthe traveling webs divided by the product pitch, or product size. Toenable use of different product sizes in a given process, the sampletiming of the inspection station results may be varied, accordingly.

In addition to synchronous sampling of the inspection station results,the results could be analyzed asynchronously, which may be advantageousif various materials are incorporated into the process at differentrates. Asynchronous analysis of the outputs, however, may provide lessvisibility into the specific defects included in a completed product.

Prior to operating or running a web process, the machinery must bethreaded with raw patch web material. The PLC 103 may provide a softwareroutine, such as an automatic web threading routine, for aiding suchsetup. An operator threads the patch web material 40 through the machineto the patch applicator 105. The operator then initiates the automaticthreading routine by using the HMI 115. The HMI 115 is coupled to thePLC 103 and the PLC 103 controls the patch applicator 105, patch cutter41, vacuum roll 42, and patch reject conveyor 107. A first number ofpatches 46 are cut by the patch cutter 41 and culled via the patchreject conveyor 107. The culled patches 46a may be a predeterminednumber from the start of the threading routine, or cut patches 46 couldbe inspected by a visual inspection station 101, and culled until thepatches 46 meet visual inspection parameters 108, as seen in FIG. 3.

Also, if the machine was shut down or paused with existing patch webmaterial loaded through the patch cutter, but a vacuum remains drawnthrough the vacuum anvil drum, the patch web material on the vacuumanvil drum will act as an air filter. The longer the patch web materialis on the drum, the dirtier it will get. Such soiled material may not beused in the construction of products for sale. Therefore, the PLC 103could provide a software routine for clearing the vacuum anvil drum ofsoiled web material. Patches that have been on the anvil for apredetermined amount of time, and therefore may have dust built up, areculled through the reject prior to machine startup. Like the automaticthreading routine, a predetermined number of patches may be culled, orthe patches may be inspected for dust build-up.

In addition to threading and anvil clearing, a placement accuracyroutine could be provided, for use on machine startup, or when theproduct configuration is changed. In a representative placement accuracyroutine, patches are placed to several startup reject products, andrelevant dimensions are taken by a visual inspection station 101 placeddownstream from the patch applicator 105. The inspection resultsindicate if and when the patch placement meets specified patch placementparameters.

During machine operation, the PLC 103, through software algorithms,determines whether a patch 46 should be placed by the patch applicator105, whether the patch 46 should be culled, or whether the web 39 shouldbe allowed to continue to run without patch placement. A patch 46 isplaced on the moving chassis web 39 only if both the patch 46 and web 39are in condition for satisfactory placement.

After machine setup and threading of any materials, the PLC 103 beginsverifying status indicators at the <application> position in memory.Generally, during machine operation, the PLC 103 controls whether apatch 46 is applied by a patch applicator 105. For each product, the PLC103 determines the action of the patch applicator 105, the patch rejectconveyor 107, and the product reject conveyor 109. For each productpresented to a patch applicator 105, the PLC 103 issues one of thefollowing commands to the patch applicator 105 and patch cutter: (1)apply patch; (2) cull patch; or (3) cull web.

The apply patch command is issued if no component part has been flaggedas defective in the composite web 39 that is presented to the patchapplicator 105 and the patch 46, itself, satisfies inspectionparameters. When the apply patch command is issued, the vacuum anvildrum 42 remains relatively stationary while the composite web 39 havinga deposited adhesive is forced by the patch applicator 105 against thepatch 46. After the patch 46 is applied, the PLC awaits the arrival ofthe next patch attachment site or product pitch.

The cull patch command is issued if a patch 46a does not meet inspectionparameters. Representative parameters can be seen in FIG. 4. Culling adefective patch 46a involves cooperation of the vacuum roll 42 and thepatch reject conveyor 107. The vacuum roll 42 preferably has a vacuummanifold that allows a release of the vacuum draw at a certain pointaround the rotation path of the roll 42. The patch reject conveyor 107may be a simple conveyor belt positioned just below the point where thevacuum draw may be removed, such that gravity causes the unapplied patch46a to fall onto the conveyor 107.

The cull web command is issued if any component part of the compositeweb 39 is flagged as defective.

The PLC 103 may also contain a unit diagnostics program, which monitorsparameters of the patch on the anvil to determine the health of thecutting knives and anvils. The unit diagnostics program involves the useof defined patch parameters measured by a vision inspection station andcompared to expected values. Information that is gathered by thediagnostics program is stored and processed in a database. Wheremeasured parameters are approaching acceptable limits, alerts are sentto the machine operator, indicating that potential problems aredeveloping. The HMI may automatically present the Unit DiagnosticsScreen for the operator to assess the situation. Furthermore, the HMImay provide graphics and charts to assist the operator by showing trenddata, measured data, and comparable data. Thus, an operator is givenadvance notice of a problem so that any corrections can be made duringthe next machine downtime. Specifically, as the knives on the patchcutter age, the patches tend to skew. Furthermore, the deviation betweensubsequent patch cut lengths is another indicator that a knife blade mayrequire replacement.

In an effort to prolong machine run-time between service and to reducestart-up rejects, an automatic anvil adjustment program may be provided.Such adjustment allows the anvil drum and knife roll to move relative toone another. Startup and shutdown rejects can result in rejections ofmany products. The movements are preferably in one millimeter incrementsover a five millimeter range. The adjustments are made as the machine isrunning to prevent wear on a single spot as well as to minimize buildupof cut web material on the anvil. In addition to the automaticadjustment, a manual override adjustment may be provided fortroubleshooting.

If the unit diagnostics program detects a pair of patches that haveparameters outside of acceptable limits, which is usually caused by acatastrophic failure of a knife or anvil, the machine operator isalerted and the HMI preferably automatically presents the UnitDiagnostics Screen for the operator to assess the situation. For everyknife or anvil that fails, two patches will be affected. Therefore, ifthe anvil roller can accompany eight patches, twenty-five percent of thepatches will fall out of acceptable limits. All patches that fall out ofthe acceptable limits are culled by way of the reject patch conveyor.All patches that fall within acceptable limits will continue to beplaced on a composite web that is otherwise indicated as appropriate forreceiving a patch. After being notified of the problem, the machineoperator will observe the HMI to verify problem. In an attempt tocorrect the problem, the operator may try an electronic anvil shift,which, if successful, will allow the process to continue. If theelectronic anvil shift does not correct the problem, the operator willrequest that the machine stop. To aid in repair or replacement of thefailed knife or anvil, the cutter and anvil drum will stop in a positionallowing easy access to the failed components. As a convenience and toenable more efficient repair of the failed components, a rapid changeout (RCO) tool or kit could be provided, such as a set of hex wrenches.The operator changes the failed part and prepares the machine torestart. The routine for automatically clearing the anvil drum may thenrun, and the unit begins attaching patches to the composite web. Thealarm that first alerted the operator of the problem is then reset,either automatically, or manually by the operator through the use of theHMI.

There may arise a situation where multiple anvils or knives appear tohave failed. In this situation, the operator is alerted to the problem,but no patches are culled. Rather, a visual inspection stationdownstream from the patch applicator is examined to determine if theretruly is a problem. If the problem is verified by the placement accuracycheck, the operator shuts down the machine and proper maintenance isperformed. If an examination of the placement accuracy inspectionstation does not confirm the purported problem, the unit diagnosticsprogram may be suspended until it can be repaired.

Although the foregoing description involves the placement of anabsorbent insert or patch onto a diaper chassis, it will be apparent tothose skilled in the art that the apparatus and process could be used toavoid unnecessary waste in the application of any sort of patch to amoving web. Other examples of patches that may be placed are tape tabpatches and reusable fasteners.

Referring now to FIGS. 5 and 6a-c, an additional embodiment of arepresentative web processing system is shown schematically andincorporating principles of the present invention. It is noted thatthroughout the web processing, inspection systems can be incorporatedvirtually anywhere, particularly at locations of raw material input intothe process.

Automatic Cuff Folding Defect Correction

Referring now to FIGS. 7-9, an automatic cuff defect correction system300 is shown. The automatic cuff defect correction system correctsdefects that might be present in a fold of non-woven material overstrands of elastic intended to be encapsulated within the fold. Forinstance, the non-woven material may come out of operative engagementwith the elastic guide rollers initially used to fold the non-woven, orthe elastic material intended to be encapsulated within the folded-overnon-woven material may instead not be contained within the folded-overnon-woven material as intended.

Referring now to FIG. 7, before entering the cuff folding system 300,the cuff material 310 is first slit into two even width strips and thenpasses through a web guide (not shown). The operator and drive side cuffwebs 310 are driven by cuff infeed drive rolls 305 and fed to cuffinfeed idler roller 307. Tape applicator correction unit 323 isoperative next to the cuff infeed drive rolls 305.

As the cuff webs 310 pass over the elastic roller guides 340, preferablytwo adhesive coated strands of elastic 320 are laid down on top of eachof the cuff webs 310 just before folding.

Referring again to FIG. 7, the adhesive is applied by glue gun 330,which is adjustable in the upstream and downstream directions byadjusters 332, and by vertical glue gun adjustment system 336, and bythe glue gun rotation system 334. In the cross-machine direction, theglue gun adjuster 338 is provided, all to assist proper adhesiveapplication to the elastics 320 being on the infeed.

As best shown on FIG. 8, the cuff fold is created by passing theoperator and drive side cuff webs 310 over elastic guide rollers 340.Part of the cuff web 310 extends over the outboard edges of elasticguide rollers 340; it is these portions of cuffs 310 that become foldedback on top of the cuff webs 310. The fold is completed as the cuff webs310 pass over the folding board 380 (FIG. 7) carrying inwardly slidablefolding plows 360 on the drive and operator sides with the elasticstrands 320 inside the fold of the non-woven material 310. The inwardlyslidable folding plows 360 are disengaged (not contacting the cuff webs310) during run conditions while no defect in the creation of the cuff(elastic 320 contained within folded over cuff web 310) and engaged withthe cuff web 310 if a defect is created, to urge the cuff web 310 toreturn to its proper folded over condition.

Referring again to FIG. 7, the cuff next passes over the cuff outfeedidler roll 308 and chill roll 390 to set the adhesive, and the cuff webs310 containing the elastics 320 within the folded over portion of thecuff webs 310 are passed on down the line for further processing,including bonding the folded-over non-woven portion of the cuff 310 tothe non-folded-over non-woven portion of the cuff 310 to firmly containthe elastics 320 within the fold (not shown), and to finally attach theformed cuff 310 containing the elastics 320 to the appropriate portionof the diaper (not shown).

Still referring to FIG. 7, vision systems 310 are provided on mounts320, in order to detect defects in the cuff formation process, and toset in motion the appropriate cuff correction process as describedbelow.

1.1 Cuff Correction Systems

The cuff folding system 300 preferably has four cuff correction modeoptions, described below.

1.1.1 Basic Cuff Correction Mode

The Basic Cuff Correction mode does not utilize the vision system 310,optional tape applicator (not shown), or optional elastic correctionrollers 350 (FIG. 8). When a splice between two rolls of incomingnon-woven material 310 is detected, the plows 360 will move between thedisengaged position (shown in phantom in FIG. 8) to the engaged position(shown in bold in FIG. 8) to allow the splice to pass through the plows360. Once the splice of non-woven material 310 has passed, the plowswill again return to the disengaged position as shown in FIG. 8.

1.1.2 Advanced Cuff Correction Mode

The Advanced Cuff Correction mode incorporates a fold correctionsequence and an elastic mistrack sequence.

The fold correction sequence engages the plows 360, the elastic mistrackcorrection rollers 350, applies tape and the cuff infeed rate isincreased to help in the correction of the fold problem. If the systemis unable to correct itself after a predetermined period, such as after5 attempts, a general machine fault can be raised.

The elastic mistrack correction rollers 350 (FIG. 8) are engaged and thecuff infeed rate is increased to help in the correction of an elasticmistrack. If the system is unable to correct itself after apredetermined period, such as after 5 attempts, a general machine faultcan be raised.

This mode supports all faults and rejects.

1.1.3 Advanced (Elastic Correction Only) Cuff Correction Mode

The Advanced (Elastic Correction Only) Cuff Correction mode includeseverything that comes with the Advanced Cuff Correction mode except forthe tape applicator.

Without the tape applicator, the fold correction sequence is differentwhile in this mode. If a fold correction is required, the plows 360 willbe engaged (by moving plows 360 slidably between the position shown indashed lines on FIG. 8, to the position shown in by plows 360 shown bysolid lines on FIG. 8). If the fold problem still exists after the plows360 are engaged, the system can raise an unable to correct cuff foldfault. If the problem no longer exists, the system will return to itsnormal running state, with the plows 360 returning to their disengagedposition (FIG. 8). This mode supports all faults and rejects.

1.1.4 Disabled

All cuff correction system monitoring and corrective action will bedisabled regardless of which option is installed.

2. Setup and adjustment

2.1 Cuff System Adjustments

2.1.1 Adhesive adjustments

As shown in FIG. 7, glue gun 330 can be adjusted in the upstream anddownstream directions by adjusters 332, and by vertical glue gunadjustment system 336, and by the glue gun rotation system 334. In thecross-machine direction, the glue gun adjuster 338 is provided, all toassist proper adhesive application by positioning and re-positioning theglue gun 330 to the elastics 320 being on the infeed.

When properly positioned, the glue gun heads 330 preferably apply somedownward pressure on the elastic strands 320 to deflect them slightly.

The cuff unit cross machine direction adjustment mechanism 352 can beused to adjust the cuff unit in the cross machine direction.

2.2 Elastic Roller Setup

Referring now to FIG. 8 the proper position/relationship between theelastic strands 320, the mistrack corrections rollers 350, elastic guiderollers 340 and plows 360 is shown.

2.3 Idler Roll Adjustments

The proper location for the cuff infeed and outfeed idler rolls areshown in FIGS. 7 and 9.

Referring to FIG. 7, the infeed idler roll 307 is preferably positionedso that the angle between a horizontal reference line tangent to the topof the guide roller 340 and a reference line tangent to the infeed idlerroll 307 and guide roller 340 is roughly 15° (α1, FIG. 7).

Still referring to FIG. 7, the outfeed idler roll 308 can be adjusted,preferably so that the angle of the folding board 308 in relation to thecuff web 310 is roughly 1° (α3, FIG. 9). If not, folding board angleadjustment 363, and associated adjustment bolts (not shown) can be usedto create a small gap (α2) between the cuff web 310 and the foldingboard 380 at its entrance.

Referring to FIGS. 7 and 9 still, the outfeed idler roll 308 ispreferably positioned so that the angle between a reference line inlinewith the top of the folding plate 380 and a reference line from the tipof the feather arrest 362 (shown in FIG. 9) and tangent to the outfeedidler roll 308 is 1° (α3, FIG. 9).

A feather arrest 358 consisting of a feather arrest block 362 and nutplate 361 is used to control buildup of process materials which resultsin product reject or process shut-down. The width of the feather arrestis preferably roughly the same as the folding board or plate 380 and,the feather arrest block 362 mounts to the underside of it by nut plate361. The feather arrest block 362 has a sloped surface which risesslightly above the plane of the folding plate 380, this causes the cuffweb 310 to contact the tip of the feather arrest block 362 (somewhatlike a scraper) as it exits the cuff folding assembly. This actionminimizes buildup. The feather arrest block 362 preferably has amirrored shape which allows it to be used a total of four times beforeneeding replacement. The cuff web 310 preferably makes contact with anoutboard edges of the feather arrest blocks 362, this allows them to beswapped out between operator and drive side folding boards 380. Themirrored shape of the feather arrest block 362 allows it to be rotated180° and remounted providing an additional use out of each featherarrest.

3. Operation

3.1 Fold Inspection

If the fold of the non-woven web 310 becomes too narrow or the web widthis out of spec on either the drive side or the operator sideindependently, the fold correction sequence is initiated. The foldcorrection sequence can be disabled if machine speed is below apredetermined speed, such as 150 ppm, and momentarily when a splice hasbeen detected.

3.2 Fold Correction Sequence

In the fold correction sequence, the plows 360 are engaged, and theelastic mistrack correction rollers 350 are engaged momentarily and thecuff infeed rate is increased to help in the correction of the foldproblem. After a brief delay to allow everything to become fullyengaged, tape can be applied to the web (not shown) to further assistcorrecting the fold defect. Should the vision system 370 detect thatcuff problems no longer exist during the brief delay, the foldcorrection sequence is aborted and tape is not applied to the web. Oncetape has been applied to the web, the system will wait long enough toevaluate whether the problem still exists, again via vision system 370.If the problem no longer exists, the plows 360 are disengaged, thecorrection attempts counter is reset, and the cuff infeed 305 isreturned to its normal rate. If the problem still exists, the aboveprocedure can be repeated, such as to a preset limit of up to a total of5 attempts. Then, if desired, if the system is unable to correct itselfafter 5 attempts, a general machine fault is raised.

3.3 Elastic Inspection

If the inner elastic strand is missing or the fold becomes too wide oneither the drive side or the operator side independently, the elasticmistrack correction sequence can be initiated. The elastic mistrackcorrection sequence is preferably disabled if the system is in the foldcorrection sequence, if the machine is not at speed set point, ormomentarily when a splice has been detected.

3.4 Elastic Mistrack Correction Sequence

In the elastic mistrack correction sequence, the elastic correctionrollers 350 are engaged momentarily and the cuff infeed rate isincreased to help in the correction of the elastic mistrack. Once therollers 350 are disengaged, the system will wait long enough to evaluatewhether the problem still exists. If the problem no longer exists, anelastic mistrack correction attempts counter is reset and the cuffinfeed 305 is returned to its normal rate. If the problem still exists,the above procedure can be repeated a predetermined number of times,such as up to a total of 5 attempts. If the system is unable to correctitself after the predetermined number of attempts, a general machinefault can be raised.

3.5 Process Response

3.5.1 Glue Gun

Intermittent glue is enabled any time speed is above a predeterminedspeed, such as 100 ppm.

3.5.2 Plows

Plows 360 are engaged when a splice is detected for a set number ofproducts to allow the splice to pass. This action is part of theAdvanced Cuff Correction Mode, Advanced (Elastic Correction Only) CuffCorrection Mode, and the Basic Cuff Correction Mode describedpreviously. In addition, the plows 360 engage during the fold correctionsequence.

3.5.3 Tape Applicator

Tape can be applied to the web during the fold correction sequence.

3.5.4 Elastic Mistrack Correction Rollers

Elastic mistrack correction rollers 350 are engaged during the elasticmistrack correction sequence. Elastic mistrack correction rollers 350are engaged at the beginning of each fold correction sequence. Elasticmistrack correction rollers 350 are engaged whenever machine speed isnot at set point with two exceptions. First, if the cameras 372 detect aneed to run the fold correction sequence, the command to engage theelastic mistrack correction rollers 350 when machine speed is not at setpoint is disabled. This allows the fold correction sequence to run likenormal. Second, the elastic mistrack correction rollers 350 will notengage during ramp-down even though the machine speed is not at setpoint during this time.

3.5.5 Reduced Tension (Increased Infeed Rate)

Under four different scenarios, the cuff infeed rate is increased by apredetermined amount, such as 0.75 mm, to reduce tension. First, if thesplicer sequence activates at the unwind of the cuff webs 310, the cuffinfeed rate is increased until the splice has passed the folding boards380. Second, whenever machine speed is not at set point, the cuff infeedrate is increased to help maintain the cuff fold. Third, if the systemever enters the fold correction sequence, the cuff infeed rate isincreased to help in the correction of the fold. Last, if the systemever enters the elastic mistrack correction sequence, the cuff infeedrate is increased to help in the correction of the elastic mistrack.

3.5.6 Ramp-Up Notes

The elastic mistrack correction rollers 350 are engaged during ramp-upbecause the machine speed is not at set point. The fold correctionsequence will take place if the need arises once machine speed equals orexceeds a predetermined amount, such as 150 ppm. If a fold correctionsequence occurs, the command to enable the elastic mistrack correctionrollers when the machine speed is not at set point is momentarilydisabled. The elastic mistrack correction sequence is disabled duringramp-up, and the cuff infeed rate is increased to help maintain the cufffold.

3.5.7 Ramp-Down Notes

The fold correction sequence will take place during ramp-down if theneed arises and the machine speed still exceeds a predetermined amount,such 150 ppm. The elastic mistrack correction sequence is disabledduring ramp-down.

3.5.8 Splice Notes

When a splice in one of the incoming cuff webs 310 is detected, theplows 360 engage and the fold correction sequence and the elasticmistrack correction sequence are disabled. The plows 360 remain engagedfor a product count long enough to allow the splice to pass through theplows and pass the vision system. Once the product count has been met,the plows 360 will disengage and the fold correction sequence and theelastic mistrack correction system will be enabled. When the splicersequence activates at the unwind, the cuff infeed rate is increaseduntil the splice has passed the folding boards.

3.6 Faults

The Advanced Cuff Correction System and the Advanced (Elastic CorrectionOnly) Cuff Correction System can raise 4 different general machinefaults. If the drive side camera 372 OK status signal is not present, acuff vision system drive side camera fault is raised. If the operatorside camera 372 OK status signal is not present, a cuff vision systemoperator side camera fault is raised. If the fold correction sequencefails to fix a detected problem in a predetermined number of attempts,it will raise an unable to correct cuff fold fault. If the elasticmistrack correction sequence fails to fix a detected problem in apredetermined number of attempts, it will raise an unable to correctcuff elastic/glue fault. Glue is noted in this fault description becausea lack of glue on the elastic strands 320 will cause the camera 372 tobe unable to detect it.

3.7 Rejects

Rejects are caused any time the system enters the fold correctionsequence or the elastic mistrack correction sequence until problems areno longer detected. Due to the nature of the vision system 372, rejectsfrom the cuff vision system have a speed dependency and need to have theoffsets and quantities set at the desired running speed. There are 8different reject reasons caused by the Advanced Cuff Correction Systemand the Advanced (Elastic Correction Only) Cuff Correction System. Theseare drive side web width out of spec, drive side fold too narrow, driveside fold too wide, drive side inner elastic strand missing, operatorside web width out of spec, operator side fold too narrow, operator sidefold too wide, and operator side inner elastic strand missing.

4. Troubleshooting

4.1 Cuff Problems Possible Causes:

-   -   Plugged up glue nozzle 330    -   Slitting cuff web 310 unevenly between drive side and operator        side    -   Fold over width set incorrectly on the drive side or operator        side    -   Buildup on the plows 360 are not allowing for fold correction    -   Buildup on the folding boards 380 is effecting fold width    -   Buildup on the feather arrest 362 is effecting fold width    -   Glue buildup in the elastic guide rollers 340    -   Glue buildup on the elastic mistrack correction roller 350    -   Camera lens 372 may need to be cleaned    -   Camera light may need to be cleaned    -   Web guide photoeyes may need to be cleaned    -   An elastic strand 320 is broken    -   Both elastic strands 320 in the same glue nozzle 330 lane    -   Chill roll 390 is not functioning    -   Cuff nip rolls (not shown) are either not engaged or covered in        buildup    -   Tape roll (not shown) is empty or web is broken    -   Folding plows 360 adjusted incorrectly for fixing a fold problem    -   Folding boards 380 are either tipped up too much or too little    -   Cuff raw material 310 may be too wide or too narrow    -   Cuff draws set incorrectly    -   Glue nozzles 330, elastic guide rollers 340, elastic mistrack        correction rollers 350, and folding plows 360 may no longer be        setup according to the cuff setup document    -   Camera light may not be functioning    -   Cameras 372 lost communication to the PLC    -   Camera 372 is no longer centered over the folded cuff    -   Either of the two camera cables are disconnected    -   Either of the two camera cables are malfunctioning    -   Camera inspection is not running    -   Camera lens is out of focus    -   Camera lens aperture setting not correct    -   Camera lens is loose    -   Camera needs to be recalibrated    -   Infrared filter is not screwed onto the lens        4.2 Corrective Actions    -   If cuff problems start occurring, a thorough cleaning of all the        cuff folding pieces can help    -   Visual verification that there is a good glue pattern on each        elastic strand 320    -   Verify that the cuff 310 is being slit evenly between the        operator and drive side and adjust the web-guide photoeyes if        needed    -   Verify that each cuff 310 is being folded over the correct        amount and adjust the web-guide photoeyes if needed    -   If problems continue to occur, the vision system 372 may need to        be checked for functionality    -   Verify the cameras 372 and light are operational    -   Verify the camera 372 is communicating with the PLC    -   To verify proper functionality of the vision system by viewing        images from the camera 372, connect to the camera using vision        software (not shown)    -   Take care not to modify the camera inspection program while        connected to the camera 372    -   Verify the cuff inspection is running

The foregoing is considered as illustrative only of the principles ofthe invention. Furthermore, since numerous modifications and changeswill readily occur to those skilled in the art, it is not desired tolimit the invention to the exact construction and operation shown anddescribed. While the preferred embodiment has been described, thedetails may be changed without departing from the invention, which isdefined by the claims.

The invention claimed is:
 1. A method for correcting defects in arunning web comprising: creating a running fold having a cross-directionfold width in an initial condition along a machine direction of arunning web supplied at a feed rate; monitoring said running fold for apredetermined change in cross-direction fold width of said fold widthfrom said initial condition; upon detection of said predetermined changein said cross-direction fold width of said fold width from said initialcondition, initiating a correction sequence to restore said running foldto said initial condition; wherein said correction sequence furthercomprises the steps of: engaging a mistrack correction roller againstthe running web; and disengaging said mistrack correction roller fromthe running web.
 2. A method according to claim 1, wherein, if said foldwidth is too narrow, said correction sequence further comprises the stepof urging a folding plow into engagement with said running web.
 3. Amethod according to claim 1, further comprising a step of increasingsaid feed rate after engaging said mistrack correction roller and thendecreasing said feed rate after the step of increasing said feed rate.4. A method according to claim 1, wherein, if the fold width is toonarrow, the correction sequence further comprises the step of applyingtape to said running web via a tape applicator, in order to correct saidfold width back to said initial fold width.
 5. A method according toclaim 1, wherein engaging said mistrack correction roller against saidrunning web is disabled if a machine speed is below a predeterminedspeed.
 6. A defect correction system for correcting defects in a fold ofa running web having elastic strands thereon, the system comprising: anarrangement of a drive roller and idle roller configured to translatethe running web in a machine direction at a feed rate; a guide rollerpositioned to receive the running web as it translates in the machinedirection; a correction roller configured to selectively engage therunning web and elastic strands; a folding board positioned downstreamfrom the guide roller and configured to create a running fold in therunning web that has a cross-direction fold width along the machinedirection; a defect detection system configured to monitor the runningfold for a predetermined change in cross-direction fold width from aninitial fold width; and a controller programmed to: receive an inputfrom the defect detection system comprising the cross-direction foldwidth of the running fold; and identify the predetermined change incross-direction fold width from the initial fold width; and wherein,when the predetermined change in cross-direction fold width isidentified, the correction roller operates to engage with the runningweb and disengage from the running web.
 7. The system of claim 6 whereinthe defect detection system comprises a camera.
 8. The system of claim 6further comprising a plow that is movable to selectively engage therunning web.
 9. The system of claim 8 wherein the plow engages therunning web when the cross-direction fold width is identified as beingnarrower than the initial fold width, in order to correct the fold widthback to the initial fold width.
 10. The system of claim 9 furthercomprising a tape applicator configured to apply tape to the running webwhen the cross-direction fold width is identified as bell narrower thanthe initial fold width, in order to correct the fold width back to theinitial fold width.
 11. The system of claim 6 wherein the drive rolleris configured to increase the feed rate of the running web when thecorrection roller engages with the running web and to decrease the feedrate of the running web when the correction roller disengages from therunning web.
 12. The system of claim 6 wherein the defect detectionsystem is configured to monitor a presence and positioning of theelastic strands on the running web to detect an absence of one or moreof the elastic strands or a mistrack of one or more of the elasticstrands on the running web.
 13. The system of claim 12 wherein thecontroller is programmed to: receive an input from the defect detectionsystem comprising the presence and positioning of the elastic strands onthe running web; and identify the absence of one or more of the elasticstrands or the mistrack of one or more of the elastic strands on therunning web.
 14. The system of claim 13 wherein, when the absence of oneor more of the elastic strands or the mistrack of one or more of theelastic strands on the running web is identified, the correction rolleroperates to engage with the running web and disengage from the runningweb.